Owing to the rapid development of digital technology, all kinds of information equipment is promptly improved and various multimedia provide people abundant digital information. With such a tide of digitalization, the utilization of touch screens has already drawn a lot of attention from users. Beginning with PDAs (Personal Digital Assistants) and small-sized 3-inch LCD (Liquid Crystal Display) for cell phones to a medium-sized 10-inch LCD for industry equipment and business terminal products, the utilization scope of the touch screen has gradually extended to large-sized screens over 10-inches.
Please direct to FIG. 1(A), which is a cross-section diagram illustrating a conventional touch panel. The touch panel 10 shown in FIG. 1(A) mainly consists of a lower conductive layer 11, an upper conductive layer 12, a double side adhesive (DSA) 13 and a plurality of spacers 14. Usually the lower conductive layer 11 is a substrate 11b that is deposited or coated with a transparent conductive substance 11a being a Indium Tin Oxide (ITO), a Fluorine Tin Oxide (FTO), an Antimony Tin Oxide (ATO) or a carbonate thereon, wherein the substrate 11b is a Poly Carbonate (PC) substrate or a glass substrate. The upper conductive layer 12 is a substrate 12b that is deposited or coated with a transparent conductive substance 12a being a ITO, a FTO, an ATO or a carbonate thereon, wherein the substrate 12b is a Poly Ethylene Terephthalate (PET) made substrate.
The plurality of spacers 14 are sandwiched between the lower conductive layer 11 and the upper conductive layer 12 for separating the lower conductive layer 11 and the upper conductive layer 12. The lower conductive layer 11 and the upper conductive layer 12 are joined together with the double side adhesive 13. The surface above the upper conductive layer 12 is a touching surface S. A user can touch or press the touching surface S to render the lower conductive layer 11 and the upper conductive layer 12 to contact making an electrical connection.
Please further direct to FIG. 1(B), which is a diagram illustrating the work principle for a conventional touch panel. There are two pairs of electrodes 13X and 13Y located at the four edges of the lower conductive layer 11. The electrode 13X and the electrode 13X are located at the opposite side of the lower conductive layer 11 and parallel to each other and similarly the electrode 13Y and the electrode 13Y are located at the opposite side of the lower conductive layer 11 and parallel to each other. The pair of electrodes 13X and the pair of electrodes 13Y are perpendicular to each other. The circuit X consists of the pair of the electrodes 13X and vice versa the circuit Y consists of the pair of the electrodes 13Y.
First a +5 volt voltage potential is input from the points E1 and E3 of the lower conductive layer 11 so as to form a standard 5 volt voltage potential between circuit X from points E1, E3 to points E2, E4 and alternatively, a 5 volt voltage potential is then input from the points E1 and E2 of the lower conductive layer 11 so as to form a standard 5 volt voltage potential between circuit Y from points E1, E2 to points E3, E4. Once a user touches or presses any position on the touching surface S, where by the lower conductive layer 11 and the upper conductive layer 12 contact and the voltage at the contact point at the respective circuits X and Y are output from the signal line L of the upper conductive layer 12. The upper conductive layer 12 could thus probe/detect/inspect the voltage signal for the touched or pressed position at the respective circuits X and Y. Then the voltage potential is transformed into a digital format, so that the coordinate for the touched or pressed position is precisely obtained. Typically, an Alternating Current (AC) having a work frequency of 150 Hz, is sufficient for probing/detecting/inspecting the touched or pressed position at any position on the touching surface S of the touch panel 10.
However, it is apparent that the above-mentioned process could be only applied for detecting a single point touch event. As for a multi-touch event, it fails. Therefore there is a need for a multi-touch, touch panel to be invented. In reference with the U.S. Pat. No. 5,815,141 and Euro Patent No. EP 0 631 256 A2, these patents provide a multiple input area independent from each other so as to receive multiple touches simultaneously, even though, it is still insufficient for a multi-touch touch panel to deal with a multiple-touch event complicated with sophisticated gestures. Hence in order to overcome the mentioned drawbacks of the prior art, a novel sensing system for a multi-touch event thereof is provided.